In one aspect, the present relates to poly(arylene sulfide) compositions. In another aspect, the present invention relates to methods of preparing articles from poly(arylene sulfide) compositions. In yet another aspect, the present invention relates to articles produced from poly(arylene sulfide) compositions.
Poly(arylene sulfide) (PAS) resins have been used in numerous applications. Due to their thermal stability, chemical resistance, and other desirable properties, PAS resins have been widely used in the production of molding compositions, coating compositions, and encapsulating compositions. Due to their desirable electrical insulating properties, PAS resins have been used in the production of electronic components and in the preparation of compositions for encapsulating electronic components.
The comparative tracking index (CTI) rating of a PAS composition provides a comparative indication of the composition's ability to perform as an electrical insulating material under wet and/or contaminated conditions. In determining the CTI rating of a resin composition, two electrodes are placed on a molded test specimen. A voltage differential is then established between the electrodes while an aqueous ammonium chloride solution is slowly dripped onto the test specimen. The CTI rating of the test specimen is the maximum electrode voltage differential at which, in five consecutive tests, more than 50 drops of the ammonium chloride solution must be applied to the test specimen in order to cause tracking to occur.
A need presently exists, particularly in the electrical appliance industry, for plastic compositions which (1) possess the thermal and chemical resistance characteristics exhibited by PAS resins and (2) have high CTI ratings. In recent years, the appliance industry has actively endeavored to develop appliances which are smaller and which provide greater power output. One of the primary techniques used in the industry to reduce the size of an appliance has been to reduce the amount and/or thickness of insulating material used in the appliance. In order to ensure that sufficient insulating capability is maintained when relatively small amounts and/or thicknesses of the insulating material are used, the insulating material must generally have a high CTI rating.